org.qtitools.qti.node.expression.general
Class Variable

java.lang.Object
  org.qtitools.qti.node.AbstractNode
      org.qtitools.qti.node.AbstractObject
          org.qtitools.qti.node.expression.AbstractExpression
              org.qtitools.qti.node.expression.general.LookupExpression
                  org.qtitools.qti.node.expression.general.Variable

All Implemented Interfaces:

java.io.Serializable, Expression, ExpressionParent, XmlNode, XmlObject, Validatable

public class Variable
extends LookupExpression

This expression looks up the value of an itemVariable that has been declared in A corresponding variableDeclaration or is one of the built-in variables. The result has the base-type and cardinality declared for the variable subject to the type promotion of weighted outcomes (see below).

During outcomes processing, values taken from an individual item session can be looked up by prefixing the name of the item variable with the identifier assigned to the item in the assessmentItemRef, separated by A period character.

For example, to obtain the value of the SCORE variable in the item referred to as Q01 you would use A variable instance with identifier Q01.SCORE.

When looking up the value of A response variable it always takes the value assigned to it by the candidate's last submission. Unsubmitted responses are not available during expression evaluation.

The value of an item variable taken from an item instantiated multiple times from the same assessmentItemRef (through the use of selection withReplacement) is taken from the last instance submitted if submission is simultaneous, otherwise it is undefined.

Author:

Jiri Kajaba

See Also:

Cardinality, BaseType, Serialized Form

Field Summary

static java.lang.String	ATTR_WEIGHT_IDENTIFIER_DEFAULT_VALUE Default value of weightIdentifier attribute.
static java.lang.String	ATTR_WEIGHT_IDENTIFIER_NAME Name of weightIdentifier attribute in xml schema.
static java.lang.String	CLASS_TAG Name of this class in xml schema.

Fields inherited from class org.qtitools.qti.node.expression.general.LookupExpression

ATTR_IDENTIFIER_NAME, IDENTIFIER_SEPARATOR

Fields inherited from class org.qtitools.qti.node.expression.AbstractExpression

logger

Fields inherited from interface org.qtitools.qti.node.expression.Expression

DISPLAY_NAME

Fields inherited from interface org.qtitools.qti.node.XmlNode

INDENT, NEW_LINE, SIMPLE_NAME_INNER_SEPARATOR, SIMPLE_NAMES_SEPARATOR

Constructor Summary

Variable(ExpressionParent parent)
Constructs expression.

Method Summary

protected Value	evaluateSelf(int depth) Evaluates this expression.
java.lang.String	getClassTag() Gets QTI class name of this node.
java.lang.String	getWeightIdentifier() Gets value of weightIdentifier attribute.
boolean	isVariable() Returns true if value of evaluation can change every evaluation call; false otherwise.
void	setWeightIdentifier(java.lang.String weightIdentifier) Sets new value of weightIdentifier attribute.
java.lang.String	toString()
protected ValidationResult	validateAttributes() Validates attributes of this node.

Methods inherited from class org.qtitools.qti.node.expression.general.LookupExpression

getFirstPart, getIdentifier, getProducedBaseTypes, getProducedCardinalities, getSecondPart, hasMoreParts, isValid, lookupDeclaration, lookupDeclaration, setIdentifier

Methods inherited from class org.qtitools.qti.node.expression.AbstractExpression

evaluate, getBaseType, getCardinality, getChildren, getFirstChild, getParent, getParentRequiredBaseTypes, getParentRequiredCardinalities, getProducedNumericalBaseTypes, getRequiredBaseTypes, getRequiredCardinalities, getRequiredSameBaseTypes, getRequiredSameCardinalities, getSecondChild, getType, getValue, isAnyChildNull, isNull, reset, validate

Methods inherited from class org.qtitools.qti.node.AbstractObject

getParentItem, getParentResult, getParentTest, setParent

Methods inherited from class org.qtitools.qti.node.AbstractNode

attrToXmlString, bodyToXmlString, getAttributes, getFullName, getIndent, getNode, getNode, getNode, getNodeGroups, getParentRoot, getSimpleName, getSourceFile, getSourceNode, getSourceString, getSourceUrl, hasChildNodes, load, load, load, load, loadAttributes, readChild, readChildren, setParent, setSourceFile, setSourceNode, setSourceString, setSourceUrl, toXmlString, toXmlString, validateChildren

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.qtitools.qti.node.XmlObject

getParentItem, getParentResult, getParentTest, setParent

Methods inherited from interface org.qtitools.qti.node.XmlNode

getAttributes, getFullName, getNodeGroups, getParentRoot, getSimpleName, getSourceFile, getSourceNode, getSourceString, getSourceUrl, hasChildNodes, load, load, load, load, setSourceFile, setSourceNode, setSourceString, setSourceUrl, toXmlString, toXmlString

Field Detail

CLASS_TAG

public static final java.lang.String CLASS_TAG

Name of this class in xml schema.

See Also:

Constant Field Values

ATTR_WEIGHT_IDENTIFIER_NAME

public static final java.lang.String ATTR_WEIGHT_IDENTIFIER_NAME

Name of weightIdentifier attribute in xml schema.

See Also:

Constant Field Values

ATTR_WEIGHT_IDENTIFIER_DEFAULT_VALUE

public static final java.lang.String ATTR_WEIGHT_IDENTIFIER_DEFAULT_VALUE

Default value of weightIdentifier attribute.

Constructor Detail

Variable

public Variable(ExpressionParent parent)

Constructs expression.

Parameters:

parent - parent of this expression

Method Detail

getClassTag

public java.lang.String getClassTag()

Description copied from interface: XmlNode

Gets QTI class name of this node.

QTI class name has very important role during loading/saving nodes.

For example: Java class name is AssessmentTest; QTI class name is assessmentTest.

Specified by:

getClassTag in interface XmlNode

Specified by:

getClassTag in class AbstractNode

Returns:

QTI class name of this node

isVariable

public boolean isVariable()

Description copied from interface: Expression

Returns true if value of evaluation can change every evaluation call; false otherwise. It checks this expression and all of its children (if any child is variable, this expression becomes variable too). Example of variable expressions: variable and outcome expressions.

Specified by:

isVariable in interface Expression

Overrides:

isVariable in class LookupExpression

Returns:

true if value of evaluation can change every evaluation call; false otherwise

getWeightIdentifier

public java.lang.String getWeightIdentifier()

Gets value of weightIdentifier attribute.

Returns:

value of weightIdentifier attribute

See Also:

setWeightIdentifier(java.lang.String)

setWeightIdentifier

public void setWeightIdentifier(java.lang.String weightIdentifier)

Sets new value of weightIdentifier attribute.

Parameters:

weightIdentifier - new value of weightIdentifier attribute

See Also:

getWeightIdentifier()

validateAttributes

protected ValidationResult validateAttributes()

Description copied from class: AbstractNode

Validates attributes of this node.

Overrides:

validateAttributes in class AbstractNode

Returns:

result of validation

evaluateSelf

protected Value evaluateSelf(int depth)

Description copied from class: AbstractExpression

Evaluates this expression. All children must be already evaluated. Contains no checks.

Specified by:

evaluateSelf in class AbstractExpression

Parameters:

depth - depth of this expression in expression tree (root's depth = 0)

Returns:

result of evaluation

toString

public java.lang.String toString()

Overrides:

toString in class AbstractExpression